frazzle, frazzled, frazzling, frazzles.verbs
transitive verb use.to wear away along the edges; fray; to exhaust physically or emotionally
intransitive verb use.to become worn away along the edges; to become exhausted physically or emotionally
frazzle.noun
a frayed or tattered condition; a condition of exhaustion

fawn1, fawned, fawning, fawns.transitive verbs
to exhibit affection or attempt to please, as a dog does by wagging its tail, whining, or cringing
fawn2 to seek favor or attention by flattery and obsequious behavior
fawner.noun
fawningly.adverb
the central meaning shared by these verbs is "to curry favor by behaving obsequiously and submissively": fawned on her superior; students apple-polishing the teacher; bootlicked to get a promotion; lawyers kowtowing to a judge; slavered over his rich uncle; toadying to members of the occupation force; nobles truckling to the king

frugal.adjective
practicing or marked by economy, as in the expenditure of money or the use of material resources; sparing; costing little; inexpensive (a frugal lunch)
frugality or frugalness.noun
frugally.adverb

furtive.adjective
characterized by stealth; surreptitious; expressive of hidden motives or purposes; shifty; secret
furtively.adverb
furtiveness.noun

fervid.adjective
marked by great passion or zeal.(a fervid patriot); extremely hot; burning
fervidly.adverb
fervidness.noun

fraternity.noun,.plural.fraternities
a body of people associated for a common purpose or interest, such as a guild; he quality or condition of being brothers; brotherliness; a group of people joined by similar backgrounds, occupations, interests, or tastes (the fraternity of bird watchers); a chiefly social organization of men students at a college or university, usually designated by Greek letters

fractional.adjective
of, relating to, or constituting a fraction; very small; insignificant; being in fractions or pieces
fractionally.adverb

forswear also foreswear.verb
forswore, forsworn, forswearing, forswears.transitive verbs
to renounce or repudiate under oath; to renounce seriously; to disavow under oath; deny; to make (oneself) guilty of perjury
intransitive use-to swear falsely; commit perjury

fagot also faggot.noun
a bundle of twigs, sticks, or branches bound together; a bundle of pieces of iron or steel to be welded or hammered into bars
fagoted also faggoted, fagoting, faggoting, fagots, faggots.transitive verbs
to collect or bind into a fagot; bundle; to decorate with fagoting

flagellum.noun,.plural.flagella
Biology – a long, threadlike appendage, especially a whiplike extension of certain cells or unicellular organisms that functions as an organ of locomotion; a whip

flagellate, flagellated, flagellating, flagellates.transitive verbs
to whip or flog; scourge; to punish or impel as if by whipping
flagellate.adjective
Biology – flagellated resembling or having the form of a flagellum; whiplike; relating to or caused by a flagellate organism
flagellate an organism, such as a euglena, that is equipped with a flagellum

flagellation.noun
the act or practice of flagellating
Biology – the flagellar arrangement on an organism

fetter.noun
a chain or shackle for the ankles or feet; something that serves to restrict; a restraint
fetter, fettered, fettering, fetters.transitive verbs
to put fetters on; shackle to restrict the freedom of; hamper

foster, fostered, fostering, fosters.transitive verbs
to advance; to promote the growth and development of; cultivate (detect and foster artistic talent); to nurse; cherish (foster a secret hope); to bring up; nurture (bear and foster offspring)
foster.adjective
providing parental care and nurture to children not related through legal or blood ties (foster parents; foster grandparents; a foster home); receiving parental care and nurture from those not related to one through legal or blood ties (foster children)

fluorine.noun
Symbol F A pale yellow, highly corrosive, poisonous, gaseous halogen element, the most electronegative and most reactive of all the elements, used in a wide variety of industrially important compounds. Atomic number 9; atomic weight 18.9984; freezing point –219.62°C; melting point –223°C; boiling point –188.14°C; specific gravity of liquid 1.108 (at boiling point); valence

feces.noun,.plural
waste matter eliminated from the bowels; excrement

fluent.adjective
able to express oneself readily and effortlessly (a fluent speaker, fluent in three languages); flowing effortlessly; polished (speaks fluent Russian, gave a fluent performance); flowing or moving smoothly; graceful (a yacht with long, fluent curves); flowing or capable of flowing; fluid
fluency.noun
fluently.adverb

forecast, forecast or forecasted, forecasting, forecasts.verbs
transitive verb use.to estimate or calculate in advance, especially to predict (weather conditions) by analysis of meteorological data; predict; to serve as an advance indication of; foreshadow
intransitive verb use.to calculate or estimate something in advance; predict the future forecast, forecaster.nouns
a prediction, as of coming events or conditions
forecastable.adjective

frank, franker, frankest.adjectives
open and sincere in expression; straightforward; clearly manifest; evident: frank enjoyment; candid
frank, franked, franking, franks.transitive verbs
to put an official mark on (a piece of mail) so that it can be sent free of charge; to send (mail) free of charge; to place a stamp or mark on (a piece of mail) to show the payment of postage; to enable (a person) to come and go freely
frank.noun
a mark or signature placed on a piece of mail to indicate the right to send it free of charge; the right to send mail free; a franked piece of mail.
frankness.noun
candid, outspoken, straightforward, open-–-these adjectives mean revealing or disposed to reveal one's thoughts freely and honestly; 'frank' implies forthrightness of expression, sometimes to the point of bluntness (you can tell me what you think and you may just as well be frank); candid stresses openness and sincerity and often suggests refusal to evade difficult or unpleasant issues

frankly.adverb
in a frank manner; candidly; in truth; honestly (frankly, I care about it)

frighten, frightened, frightening, frightens.verbs
transitive verb use.to fill with fear; alarm; to drive or force by arousing fear
intransitive verb use.to become afraid
frightener.noun
frighteningly.adverb

fright.noun
something extremely unsightly, alarming, or strange (brush your hair; you look a fright); sudden, intense fear, as of something immediately threatening; alarm; fear
fright, frighted, frighting, frights.transitive verbs
to frighten

frightful.adjective
causing disgust or shock; horrifying; causing fright; terrifying; excessive; extreme (a frightful storm); disagreeable; distressing (frightful weather)
frightfully.adverb
frightfulness.noun